Protected by a mutation
While investigating a case of a persistent bacterial infection in a six-week-old baby, researchers at St. Jude Children’s Research Hospital, USA, have uncovered a mutation in vancomycin-resistant Enterococcus faecium (VRE) that allows it to survive last resort antibiotic treatment. The mutation appears to trigger increased levels of a signalling molecule called alarmone, which helps VRE under stress to tolerate antibiotics, but usually this isn’t enough to fight off linezolid and daptomycin, two last resort antibiotics used to treat VRE infection. A further study showed that the formation of biofilms – colonies of bacteria that stick together – made it difficult for treatments to get through and prevented the drugs from working. As biofilms often form on medical devices such as catheters and heart valves, this finding helps towards understanding the impact of potential mutations in already resistant bacteria.